This invention relates to a liquid fuel pumping apparatus of the kind comprising a rotary distributor member mounted in a pump body and arranged in use to be driven in timed relationship with an associated engine to which it is intended to supply fuel, an annular cam ring surrounding the distributor member, the cam ring having cam lobes formed on its internal peripheral surface, for imparting inward movement to a pumping plunger mounted in a transverse bore in the distributor member in turn as the distributor member rotates, fuel being displaced from the bore during the inward movement of the pumping plunger and being supplied to the injection nozzles in turn of the associated engine, a fluid pressure operable piston for moving the cam ring angularly about the axis of rotation of the distributor member to adjust the timing of fuel delivery and coupling means connecting the piston with the cam ring.
The usual form of coupling means comprises a peg which is secured to the cam ring, the peg having a spherical end which locates in a circular recess in the side wall of the piston. The conventional practice is to secure the peg with a screw thread and to provide a complementarily threaded aperture in the cam ring into which the peg is screwed. The peg has to absorb the reaction force which is imparted to the cam ring as a cam follower associated with the plunger engages the cam lobes. As the pressure at which fuel is delivered to the associated engine is increased the reaction force is increased. The construction as described cannot be strengthened to any significant extent without substantial re-design of the apparatus and the object of the present invention is to provide a coupling means in a simple and convenient form.